What are the precautions when taking hydrocodone and chlorpheniramine (Tussionex)?

Before taking this product, tell your doctor or pharmacist if you are allergic to hydrocodone or chlorpheniramine; or to dexchlorpheniramine; or to hydromorphone; or if you have any other allergies. This product may contain inactive ingredients (including sulfites such as sodium metabisulfite), which can cause allergic reactions or other problems. Talk to your pharmacist for more details.